Repetitive Transcranial Magnetic Stimulation (rTMS) has been used to improve symptoms of mental disorders and to improve brain function. rTMS uses high energy magnetic pulses from a magnetic field generator that is positioned close to a person's head, so that the magnetic pulses affect a desired treatment region within the brain. Traditionally, the pulses are generated at a fixed frequency for a short time duration. For example, a typical rTMS system may generate pulses at 10 Hz for a duration of 6 seconds. A series of pulses generated over a period of time is referred to as a pulse train. An rTMS treatment session may be composed of several pulse trains, with a rest period between each pulse train. A typical rest period may be 54 seconds, such that 6 seconds of rTMS pulses are generated per minute.
The brain's neural oscillations arise from synchronous and coherent electrical activity, and can be recorded using an electroencephalogram (EEG). The dominant EEG oscillation in the range of 8-13 Hz is the Intrinsic Alpha Frequency (IAF), and can vary between individuals and over time. It has been disclosed by Phillips and Jin (U.S. Pat. No. 8,475,354) that providing magnetic pulses at a frequency that matches a person's IAF can provide an added benefit to the person when compared to rTMS at an arbitrary frequency, such as 10 Hz. In addition, it has been disclosed by Jin (U.S. Pat. No. 9,308,385) that rTMS pulses at a harmonic of a non-EEG biological metric, such as heart rate, that is close to the person's IAF may also provide an added benefit. It is evident that an optimal pulse frequency exists to provide maximum benefit from rTMS for a person.